Exploring apolipoprotein C-III: pathophysiological and pharmacological relevance

Hepatic Abnormal Secretion of Apolipoprotein C3 Promotes Inflammation in Aortic Dissection

BACKGROUND

Apolipoprotein C3 (apo C3) is primarily secreted by the liver and is involved in promoting sterile inflammation and organ damage under pathological conditions. Previous studies have shown that apo C3 is abundant in the plasma exosomes of patients with aortic dissection (AD), but its specific role in AD remains unclear.

METHODS AND RESULTS

In vivo, adeno-associated virus was used to knock down hepatic apo C3 expression in an AD mouse model to assess the impact of liver-derived apo C3 on the development of AD. In vitro, recombinant apo C3 protein was added to the culture medium of J774A.1 macrophages to evaluate its effect on macrophage polarization and to identify the underlying mechanisms. Additionally, the effect of apo C3 on the function of aortic endothelial and smooth muscle cells was explored. Apo C3 in the aortas of AD mice was found to originate from abnormal hepatic secretion, which enters the bloodstream and subsequently deposits in the aorta. Adeno-associated virus-mediated hepatic apo C3 knockdown significantly reduced AD incidence (P=0.0036), macrophage infiltration (P=0.0004), and collagen deposition in the aorta (P=0.0016). Similarly, inhibiting the apo C3 receptor Toll-like receptor 2 significantly lowered AD incidence (P=0.0352). In vitro, recombinant apo C3 protein promoted M1 polarization and matrix metalloproteinase secretion in macrophages by activating the Toll-like receptor 2/NLR family pyrin domain containing 3 pathway. Additionally, apo C3 increased adhesion molecule expression in endothelial cells and induced inflammation, chemotaxis, and apoptosis in vascular smooth muscle cells.

CONCLUSIONS

Our findings highlight the role of abnormally secreted hepatic apo C3 in promoting aortic inflammation.

Exploring omics signature in the cardiovascular response to semaglutide: Mechanistic insights and clinical implications

BACKGROUND

Semaglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist, is a widely used drug for the treatment of type 2 diabetes that offers significant cardiovascular benefits.

RESULTS

This review systematically examines the proteomic and metabolomic indicators associated with the cardiovascular effects of semaglutide. A comprehensive literature search was conducted to identify relevant studies. The review utilizes advanced analytical technologies such as mass spectrometry and nuclear magnetic resonance (NMR) to investigate the molecular mechanisms underlying the effects of semaglutide on insulin secretion, weight control, anti-inflammatory activities and lipid metabolism. These "omics" approaches offer critical insights into metabolic changes associated with cardiovascular health. However, challenges remain such as individual variability in expression, the need for comprehensive validation and the integration of these data with clinical parameters. These issues need to be addressed through further research to refine these indicators and increase their clinical utility.

CONCLUSION

Future integration of proteomic and metabolomic data with artificial intelligence (AI) promises to improve prediction and monitoring of cardiovascular outcomes and may enable more accurate and effective management of cardiovascular health in patients with type 2 diabetes. This review highlights the transformative potential of integrating proteomics, metabolomics and AI to advance cardiovascular medicine and improve patient outcomes.

Oxidised Apolipoprotein Peptidome Characterises Metabolic Dysfunction-Associated Steatotic Liver Disease

BACKGROUND

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) encompasses a spectrum of histological conditions ranging from simple steatosis to fibrosing steatohepatitis, and is a risk factor for cardiovascular diseases (CVD). While oxidised apolipoproteins A and B have been linked to obesity and CVD, the association between other oxidised apolipoproteins and MASLD is yet to be established. To fill this gap, we characterised the circulating serum peptidome of patients with MASLD.

METHODS

We studied the serum of 87 biopsy-confirmed MASLD patients and 20 age- and sex-matched control (CTRL) subjects. We first employed an untargeted LC-MS/MS peptidomics approach (9 CTRL, 32 MASLD) to identify key hits differentially modulated, and subsequently validated the most relevant findings through targeted peptidomics in an enlarged study population (87 MASLD and 20 CTRL).

RESULTS

Untargeted serum peptidomics identified several oxidised apolipoprotein peptide fragments, including ApoE and ApoC-III, significantly upregulated in MASLD compared to CTRL. Specifically focusing on the oxidative status of intact ApoC-III, studied through its major glycoforms (ApoC-III0, ApoC-IIIi and ApoC-IIIii), we observed a marked reduction in non-oxidised forms of these circulating peptides alongside substantially increased levels of their oxidised proteoforms in MASLD versus controls (but not within the disease stages). Oxidised ApoE and ApoC-III peptide fragments were also significantly correlated with obesity, insulin resistance, dyslipidaemia and transaminases, suggesting a potential link between circulating apolipoprotein oxidation and systemic/hepatic metabolic dysfunction.

CONCLUSION

Our data reveals a previously unreported oxidised apolipoprotein profile associated with MASLD. The functional and clinical implications of these findings warrant further mechanistic investigation.

Exploring neutrophils as therapeutic targets in cardiometabolic diseases

Current therapies for diabetes and atherosclerotic cardiovascular diseases (ACVDs) mainly target metabolic risk factors, but often fall short in addressing systemic inflammation, a key driver of disease onset and progression. Advances in our understanding of the biology of neutrophils, the cells that are principally involved in inflammatory situations, have highlighted their pivotal role in cardiometabolic diseases. Yet, neutrophils can reprogram their immune-metabolic functions based on the energetic substrates available, thus influencing both tissue homeostasis and the resolution of inflammation. In this review, we examine the effects of canonical therapies for cardiometabolic diseases on the key molecular pathways through which neutrophils respond to inflammatory stimuli. In addition, we explore potential synergies between these established therapeutic approaches and the anti-inflammatory therapies being evaluated for repurposing in the treatment of cardiometabolic diseases.

Plozasiran for Managing Persistent Chylomicronemia and Pancreatitis Risk

BACKGROUND

Persistent chylomicronemia is a genetic recessive disorder that is classically caused by familial chylomicronemia syndrome (FCS), but it also has multifactorial causes. The disorder is associated with the risk of recurrent acute pancreatitis. Plozasiran is a small interfering RNA that reduces hepatic production of apolipoprotein C-III and circulating triglycerides.

METHODS

In a phase 3 trial, we randomly assigned 75 patients with persistent chylomicronemia (with or without a genetic diagnosis) to receive subcutaneous plozasiran (25 mg or 50 mg) or placebo every 3 months for 12 months. The primary end point was the median percent change from baseline in the fasting triglyceride level at 10 months. Key secondary end points were the percent change in the fasting triglyceride level from baseline to the mean of values at 10 months and 12 months, changes in the fasting apolipoprotein C-III level from baseline to 10 months and 12 months, and the incidence of acute pancreatitis.

RESULTS

At baseline, the median triglyceride level was 2044 mg per deciliter. At 10 months, the median change from baseline in the fasting triglyceride level (the primary end point) was -80% in the 25-mg plozasiran group, -78% in the 50-mg plozasiran group, and -17% in the placebo group (P<0.001). The key secondary end points showed better results in the plozasiran groups than in the placebo group, including the incidence of acute pancreatitis (odds ratio, 0.17; 95% confidence interval, 0.03 to 0.94; P = 0.03). The risk of adverse events was similar across groups; the most common adverse events were abdominal pain, nasopharyngitis, headache, and nausea. Severe and serious adverse events were less common with plozasiran than with placebo. Hyperglycemia with plozasiran occurred in some patients with prediabetes or diabetes at baseline.

CONCLUSIONS

Patients with persistent chylomicronemia who received plozasiran had significantly lower triglyceride levels and a lower incidence of pancreatitis than those who received placebo. (Funded by Arrowhead Pharmaceuticals; PALISADE ClinicalTrials.gov number, NCT05089084.).

Differential effects of volanesorsen on apoC-III, triglycerides and pancreatitis in familial chylomicronemia syndrome diagnosed by genetic or non-genetic criteria

BACKGROUND

Familial chylomicronemia syndrome (FCS) is diagnosed by genetic or non-genetic criteria.

OBJECTIVE

To assess responses to treatment of apolipoprotein (apo)C-III, triglycerides, and pancreatitis events in patients with FCS-based diagnostic methods.

METHODS

APPROACH enrolled 66 patients with FCS randomized to volanesorsen or placebo for 12 months. In 50 participants, genetic confirmation of FCS was based on the presence of pathogenic bi-allelic variants in LPL, APOC2, APOA5, GPIHBP1, or LMF1 genes. In 16 participants without a genetic diagnosis, FCS was diagnosed using clinical criteria and post-heparin lipoprotein lipase activity ≤20 % of normal. Plasma levels of apoC-III, triglycerides and related variables were measured at 3, 6 and 12 months.

RESULTS

No significant differences were present in mean apoC-III reductions with volanesorsen at 3, 6 or 12 months in patients with FCS diagnosed either genetically or non-genetically. In contrast, the triglyceride reductions were statistically less robust in patients with genetic diagnosis at each timepoint, with mean (95 % confidence interval) percent reduction in triglycerides of -68.7 % (-78.7, -58.6) vs. -84.0 % (-99.4, -68.6), p = 0.014 at Month 3; -58.2 % (-78.1, -38.2) vs. -84.5 % (-122.4, -46.7), p = 0.009 at Month 6; and -35.6 % (-57.7, -13.4) vs. -69.0 % (-105.0, -33.1), p = 0.005 at Month 12. Patients with a genetic diagnosis had significantly lower response rates for achieved triglycerides <500 mg/dL, <750 mg/dL, <880 mg/dL and <1000 mg/dL than patients with a non-genetic diagnosis. All 5 episodes of acute pancreatitis occurred in patients with a genetic diagnosis.

CONCLUSIONS

For a similar reduction in apoC-III in response to volanesorsen, triglyceride reduction is attenuated in patients with genetically versus non-genetically diagnosed FCS.

New drugs for treating dyslipidemias. From small molecules to small interfering RNAs

Despite the various therapeutic tools available, many patients do not achieve therapeutic goals, and cardiovascular diseases remain a significant cause of death in our setting. Furthermore, even in patients who manage to reduce their LDL-C levels to the recommended targets, cardiovascular events continue to occur. The therapeutic challenge and the persistent risk have led to active research into new drugs targeting novel therapeutic pathways in the field of lipoprotein metabolism disorders. The therapeutic approach involves new pharmacological mechanisms, ranging from small molecules and monoclonal antibodies to RNA interference, with inclisiran being the first drug approved for clinical use in the cardiovascular domain. In this review, we aim to provide a comprehensive overview of the new therapeutic targets and pharmacological mechanisms under development, as well as their potential clinical impact.

Multifaceted Role of Apolipoprotein C3 in Cardiovascular Disease Risk and Metabolic Disorder in Diabetes

Apolipoprotein C3 (APOC3) plays a critical role in regulating triglyceride levels and serves as a key predictor of cardiovascular disease (CVD) risk, particularly in patients with diabetes. While APOC3 is known to inhibit lipoprotein lipase, recent findings reveal its broader influence across lipoprotein metabolism, where it modulates the structure and function of various lipoproteins. Therefore, this review examines the complex metabolic cycle of APOC3, emphasizing the impact of APOC3-containing lipoproteins on human metabolism, particularly in patients with diabetes. Notably, APOC3 affects triglyceride-rich lipoproteins and causes structural changes in high-, very low-, intermediate-, and low-density lipoproteins, thereby increasing CVD risk. Evidence suggests that elevated APOC3 levels-above the proposed safe range of 10-15 mg/dL-correlate with clinically significant CVD outcomes. Recognizing APOC3 as a promising biomarker for CVD, this review underscores the urgent need for high-throughput, clinically feasible methods to further investigate its role in lipoprotein physiology in both animal models and human studies. Additionally, we analyze the relationship between APOC3-related genes and lipoproteins, reinforcing the value of large-population studies to understand the impact of APOC3 on metabolic diseases. Ultimately, this review supports the development of therapeutic strategies targeting APOC3 reduction as a preventive approach for diabetes-related CVD.

Hypertriglyceridemia Therapy: Past, Present and Future Perspectives

Hypertriglyceridemia therapy is essential for preventing cardiovascular diseases. Fibrates belong to an important class of lipid-lowering drugs useful for the management of dyslipidaemia. By acting on the peroxisome proliferator-activated receptor (PPAR)-α, these drugs lower serum triglyceride levels and raise high-density lipoprotein cholesterol. Fibrate monotherapy is associated with a risk of myopathy and this risk is enhanced when these agents are administered together with statins. However, whereas gemfibrozil can increase plasma concentrations of statins, fenofibrate has less influence on the pharmacokinetics of statins. Pemafibrate is a new PPAR-α-selective drug considered for therapy, and clinical trials are ongoing. Apart from this class of drugs, new therapies have emerged with different mechanisms of action to reduce triglycerides and the risk of cardiovascular diseases.

ANGPTL3 and ApoC-III inhibitors for treating hypertriglyceridemia in context: horses for courses?

PURPOSE OF REVIEW

Hypertriglyceridemia (HTG) is an independent and casual risk factor for atherosclerotic cardiovascular disease (ASCVD). There is an unmet need for more effective treatments for patients with HTG. Angiopoietin-like protein 3 (ANGPTL3) and apolipoprotein C-III (apoC-III) are key regulators of triglyceride-rich lipoprotein (TRL) metabolism. We review recent clinical trials targeting ANGPTL3 and apoC-III with monoclonal antibody and nucleic acid therapies, including antisense oligonucleotides and small interfering RNA.

RECENT FINDINGS

ANGPTL3 and apoC-III inhibitors are effective in lowering plasma triglycerides and TRLs, with possibly greater efficacy with the inhibition of apoC-III. By contrast to ANGPTL3 inhibition that has the advantage of greater lowering of plasma low-density lipoprotein (LDL)-cholesterol and apoB levels, apoC-III inhibition only has a modest or no effect in lowering plasma LDL-cholesterol and apoB concentrations. Therapeutic inhibition of ANGPTL3 and apoC-III can correct HTG possibly by reducing production and increasing catabolism of TRL particles, but this remains to be formally investigated in patients with HTG.

SUMMARY

Novel agents targeting ANGPTL3 and apoC-III can correct HTG and potentially lower risk of ASCVD in patients with HTG. The long-term safety and cost-effectiveness of these agents await confirmation in ongoing and future studies.

A novel mouse model of familial combined hyperlipidemia and atherosclerosis

Within the context of residual cardiovascular risk in post-statin era, emerging evidence from epidemiologic and human genetic studies have demonstrated that triglyceride (TG)-rich lipoproteins and their remnants are causally related to cardiovascular risk. While, carriers of loss-of-function mutations of ApoC3 have low TG levels and are protected from cardiovascular disease (CVD). Of translational significance, siRNAs/antisense oligonucleotide (ASO) targeting ApoC3 is beneficial for patients with atherosclerotic CVD. Therefore, animal models of atherosclerosis with both hypercholesterolemia and hypertriglyceridemia are important for the discovery of novel therapeutic strategies targeting TG-lowering on top of traditional cholesterol-lowering. In this study, we constructed a novel mouse model of familial combined hyperlipidemia through inserting a human ApoC3 transgene (hApoC3-Tg) into C57BL/6 J mice and injecting a gain-of-function variant of adeno-associated virus-proprotein convertase subtilisin/kexin type 9 (AAV-PCSK9)-D377Y concurrently with high cholesterol diet (HCD) feeding for 16 weeks. In the last 10 weeks, hApoC3-Tg mice were orally treated with a combination of atorvastatin (10 mg·kg-1·d-1) and fenofibrate (100 mg·kg-1·d-1). HCD-treated hApoC3-Tg mice demonstrated elevated levels of serum TG, total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C). Oral administration of atorvastatin and fenofibrate significantly decreased the plaque sizes of en face aorta, aortic sinus and innominate artery accompanied by improved lipid profile and distribution. In summary, this novel mouse model is of considerable clinical relevance for evaluation of anti-atherosclerotic drugs by targeting both hypercholesterolemia and hypertriglyceridemia.